Porposal: provide functions without index such as Map about lo

[geritol]

agree, it can provide much cleaner transformation functions also (if you have an fn for transforming the individual items).
ie.:

func transformList(ns []int) []string {
 // return lo.Map(ns, transform)
 return lo.Map(ns, func(item int, _ int) string {
    return transform(item)
  }
}

func transform(n int) string {
  return fmt.Sprintf("%d", n)
}

[geritol]

seems to be duplicate of #263